1. Field of the Invention
The present invention relates to a medical digital ultrasonic imaging apparatus capable of storing and reusing the RF ultrasound pulse echoes, in which each RF ultrasound pulse echo received from a plurality of transducer elements is stored in order to implement an ultrasonic image of at least one frame, and the stored data are signal-analyzed, to thereby control the system according to the analysis result so that an optimal ultrasonic image can be implemented.
2. Description of the Related Art
FIG. 1 is a block diagram showing a configuration of a general medical digital ultrasonic imaging apparatus.
In FIG. 1, a main central processing unit (CPU) 100 controls the entire ultrasonic imaging apparatus according to user""s instruction via a control panel 110. A transmitter 101 applies a transmission pulse to N elements of an array transducer. A receiver 102 receives a RF ultrasound pulse echo (referred to a RF signal) reflected and returned from an object to each transducer element. The receiver 102 consists of a pre-amplifier, a time gain compensation (TGC) amplifier, and a filter for each array element. A beamforming unit 103 performs a dynamic focusing of the receiver 102 outputs with respect to all image points thereof in order to improve a resolution of an ultrasonic image. An ultrasonic echo processor 104 receives the focused signal and performs a series of a signal processing operations in order to obtain various modalities of ultrasonic images. A color flow (CF) processor 105 and a scan converter 106 receive the signal output from the ultrasonic echo processor 104 and implement a two-dimensional CF image and a B-mode image, respectively. A Doppler processor 108 receives the signal output from the ultrasonic echo processor 104 and a continuous wave/ElectroCadioGram (CW/ECG) unit 107 and implements a spectral Doppler waveform. An video/audio signal processor 109 processes the video/audio signal outputs from the CF processor 105, the scan converter 106 and the Doppler processor 108 and the results are output to a screen/speaker 111 or a recorder 112 for recording. Also, the video signal and the audio signal which have been recorded on the recorder 112 are output to the screen/speaker 111 as needed by a user.
FIG. 2 is a detailed block diagram showing the configuration of the beamforming unit 103 of FIG. 1.
The beamforming unit 103 of FIG. 2 includes an analog-to-digital (A/D) converter 11 which samples the received RF signals for N tranducer elements and a beamformer 12 for focusing the A/D converter 11 outputs and outputting the focused result.
The A/D converter 11 is comprised of a plurality of A/D converters 13. Here, nth A/D converter 13(n) receives the RF signal received at nth transducer element among the N transducer elements from a receiver which is not shown in FIG. 2 and samples the received RF signal.
The beamformer 12 includes a plurality of time/phase delay unit 14, a plurality of buffers 15 and an a summer 16. Here, the nth time/phase delay unit 14(n) receives the data output from the nth A/D converter 13(n) and stores the received data temporarily in the nth buffer 15(n) of small capacity. A first-in-first-out (FIFO) memory or a two-port memory is used as a buffer. The data output from each A/D converter is sequentially stored in each corresponding buffer. Thus, each buffer is capable of storing data necessary for time delay or phase delay.
When all data for focusing the RF signal at a desired image point are input to the nth buffer 15(n), the nth time/phase delay unit 14(n) impose the focusing delays on the data stored in the corresponding nth buffer 15(n). The time and/or phase-delayed data are summed by an adder 16 to finish the focusing process.
The data output from each A/D converter 13, which are stored in each buffer 15 are continuously changed since the focusing delay for each element changes with a depth. Generally, the data output from each A/D converter 13 and stored in each buffer 15 disappears if a focusing process is completed, and thus cannot be re-used. Also, an accurate focusing of the RF signals received from a plurality of the transducer elements is not accomplished due to the waveform distortion that occurs due to various physical phenomena as the ultrasound travels in an object. Thus, in most cases, it is not possible to actually obtain an ultrasonic image with the best resolution that can be achieved theoretically.
To solve the above problems, it is an object of the present invention to provide a method for storing each RF ultrasound pulse echo received from a plurality of transducer elements in order to implement an ultrasonic image of at least one frame.
It is another object of the present invention to provide a medical digital ultrasonic imaging apparatus that can analyze and reuse the stored RF ultrasound pulse echoes to further enhance the ultrasonic image.
To accomplish the above object of the present invention, there is provided a storing method for using RF ultrasound pulse echoes received from a plurality of transducer elements in a digital ultrasonic imaging system, the storing method comprising the steps of: (a) sampling each RF ultrasound pulse echo; and (b) storing the sampled data for implementing an ultrasonic image of at least one frame.
There is also provided a medical digital ultrasonic imaging apparatus for focusing each RF ultrasound pulse echo received from a plurality of transducer elements and implementing an ultrasonic image, the medical digital ultrasonic imaging apparatus comprising: a receiver for converting each RF ultrasound pulse echo into an electrical signal and outputting the converted result; beamforming unit for sampling each of the RF ultrasound pulse echoes output from the receiver, storing the sampled data for implementing an ultrasonic image of at least one frame, focusing the sampled data or the stored sampled data and outputting the focused result; a signal processor for receiving the focused signal from the beamforming unit and performing a series of signal processing for implementing the ultrasonic image; and a controller for controlling the entire apparatus.